SQL

Question 1

What is PostgreSQL and what are some alternative relational databases?

Answer 1

open source relational database management system

Question 2

What are some advantages of learning a relational database?

Answer 2

widely used.

data is also unlikely to be corrupted

Question 3

What is one way to see if PostgreSQL is running?

Answer 3

top

sudo service postgresql status

Question 4

What is a database schema?

Answer 4

A collection of tables is called a schema. the rules for how a data is sorted

Question 5

What is a table?

Answer 5

Relational databases store data in relations, commonly referred to as tables. A table is a list of rows each having the same set of attributes

Question 6

What is a row?

Answer 6

A table is a list of rows each having the same set of attributes
each row has a list of attributes
each row has the same list of attributes but they probably will have different values

Question 7

How do you add a row to a SQL table?

Answer 7

insert into

Question 8

What is a tuple?

Answer 8

a list of values (for columns) is referred to as a tuple.

example: values (‘Ostrich Pillow’, ‘Feel comfy and cozy!’, 99, ‘self care’)

Question 9

How do you add multiple rows to a SQL table at once?

Answer 9

example:
insert into “products” (“name”, “description”, “price”, “category”)
values (‘Ostrich Pillow’, ‘Feel comfy and cozy!’, 99, ‘self care’),
(‘Tater Mitts’, ‘Scrub some taters!’, 6, ‘cooking’)
returning *;

Question 10

How do you get back the row being inserted into a table without a separate select statement?

Answer 10

returning *

Question 11

How do you update rows in a database table?

Answer 11

update clause

Question 12

Why is it important to include a where clause in your update statements?

Answer 12

because without that, it will update every row

Question 13

How do you delete rows from a database table?

Answer 13

delete clause

Question 14

How do you accidentally delete all rows from a table?

Answer 14

using delete without a where clause

Question 15

What is a foreign key?

Answer 15

a column that is also represented in another table. these columns match each other and can be used to join other tables together

Question 16

How do you join two SQL tables?

Answer 16

join and using clause

Question 17

How do you temporarily rename columns or tables in a SQL statement?

Answer 17

as clause
select "products"."name" as "product",
       "suppliers"."name" as "supplier"
  from "products"
  join "suppliers" using ("supplierId");

Question 18

What is SQL and how is it different from languages like JavaScript?

Answer 18

SQL is declarative

Javascript is imperative

Question 19

How do you retrieve specific columns from a database table?

Answer 19

select “thing”

Question 20

How do you filter rows based on some specific criteria?

Answer 20

where clause just has to evaluated true or false

Question 21

What are the benefits of formatting your SQL?

Answer 21

easier to read

Question 22

What are four comparison operators that can be used in a where clause?

Answer 22

=, , !

Question 23

How do you limit the number of rows returned in a result set?

Answer 23

limit clause

Question 24

How do you retrieve all columns from a database table?

Answer 24

*

Question 25

How do you control the sort order of a result set?

Answer 25

order by

Question 26

What are some examples of aggregate functions?

Answer 26

sum()
average()
count()
max()
min()

Question 27

What is the purpose of a group by clause?

Answer 27

arrange